Fate of the Fallen by Quinn Blackbird

Blake counts down her final year at school before she can high-tail it out of the swampy, crime-ridden Belle Vue, and head to a big city of dreams and lights.
But her last high school year is anything other than normal.
Friends turning foes, enemies turning allies, and a dangerous, mysterious newcomer changes all that she ever imagined she knew.
Blake faces off with the future of – not just Belle Vue, but – the world, when her closest friend becomes its biggest threat.